Viscous liquid conveying apparatus

ABSTRACT

Apparatus for conveying a viscous liquid from a tank through a supply line to a device to be supplied with such liquid and thence to the tank via a return line, the liquid being heated either in the supply line or in the return line, or both. The apparatus includes concentric conduits extending into the tank and establishing supply and return passages connected respectively to the supply line and the return line. The conduits terminate at different levels inside the tank and the shorter of the conduits carries a sleeve at that end which is inside the tank and which is adjustable from outside the tank so as to vary the effective length of such conduit to enable the lower end of either conduit to extend beyond the lower end of the other conduit.

DESCRIPTION OF THE INVENTION

This invention relates to viscous liquid conveying apparatus and moreparticularly to apparatus for supplying fuel oil to a fuel oil burner,for example, the oil being supplied to the pump at a rate in excess ofthe capacity of the burner and the excess oil being returned to thetank.

Oil fired furnaces and boilers conventionally are supplied with fuel oilfrom a tank which is buried or otherwise installed outside the buildingin which the furnace or boiler is located. Oil from the tank is suppliedto the burner via a supply line and at a rate in excess of theconsumption of the burner. The excess oil is returned to the tank via areturn line. The supply and return lines often are exposed tosubstantial changes in ambient temperature. As the temperaturedecreases, the viscosity of the oil increases, thereby affecting theefficiency of the oil conveying system. This problem has been recognizedheretofore and numerous proposals have been advanced for its solution.For example, U.S. Pat. No. 2,224,403 discloses an oil storage andconveying system wherein the oil supply and return lines are heatedelectrically so that oil passing through those lines becomes heated andflows more readily.

Oil returned to the tank via the return line generally is less viscousthan the reservoir of oil inasmuch as the returned oil has been heated.It has been the practice heretofore to utilize the heat of the returnedoil to lower the viscosity of the reservoir oil in the immediatevicinity of the inlet opening of the oil supply line. Heating of the oilin the immediate vicinity of the inlet to the supply line facilitatesthe introduction of the oil to the conveying system. To avoiddissipation of the heat of the returned oil to areas of the reservoirwhere the heating of the oil would have no particular benefit, it hasbeen the practice heretofore to return the heated oil to the reservoirvia a pipe which surrounds that portion of the supply line which extendsinto the reservoir and to cause the lower end of the return pipe toproject somewhat beyond the lower end of the supply line. The lower endof the return line thus forms a cowl around the inlet to the supply lineso that the heated oil is the first to be readmitted to the supply line.

The extent to which the lower end of the return line projects beyond thecorresponding end of the supply line is an important consideration ifthe maximum efficiency is to be achieved. Some kinds and grades of oilsrequire different heat treatment in order to achieve their mostefficient flow. That is, some oils require the application of heat for agreater period of time than is required by other oils to reachacceptable flow characteristics. The time to which oil in a tank isexposed to the heat of returned oil is directly related to the extent towhich the return line extends beyond the supply line. Thus, if thereturn line projects, say, three inches beyond the end of the supplyline, the amount of the returned oil which can escape the return linebefore being reintroduced to the supply line will be relatively small,thereby enabling only a relatively small amount of reservoir oil to beheated by the return oil and for only a relatively short time.Conversely, if the return line projects only one inch beyond the supplyline, a greater quantity of the returned oil will escape the return lineso as to heat a greater quantity of the reservoir oil and for a longerperiod of time.

Until fairly recently the particular kind and grade of oil to beconsumed at a particular installation could be selected with assurancethat the continued supply of such fuel would be available in the future.More recently, however, the kinds of fuel oils which may be burned havebeen the subject of legislative and other regulatory restrictions so asto minimize atmospheric pollution. Those fuel oil systems which wereinstalled prior to the required change in the kinds of oil whichthereafter could be utilized almost invariably require a change to bemade in the relationship between the supply line and the return line. Inmost instances, this modification necessitates excavation to obtainaccess to the supply and return lines, disconnection of those portionsof such lines which enter the tank from other portions of the lines, andphysical modification or replacement of the tank-immersed lines. Such anundertaking is expensive. Moreover, the most efficient relationshipbetween the supply and return lines can be determined only empiricallywith the result that either extensive on site tinkering is required ormaximum efficiency is sacrificed. Even in those instances in which thebest possible relationship between the supply and return lines isachieved for a given season, seasonal changes, as well as subsequentfuel oil modifications, may require further adjustment of the supply andreturn lines thereby necessitating repetition of the adjustmentprocedures.

An object of this invention is to provide apparatus for conveyingviscous liquids, such as fuel oil, to and from a reservoir and whereinconcentric supply and return conduits located in the reservoir may havetheir relative positions adjusted axially from outside the reservoir toany one of a number of selected positions of adjustment.

Another object of the invention is to provide apparatus of the characterdescribed which does not interfere in any way with the normal operationof the system in which it is incorporated and which is economical tomanufacture and simple to use.

Other objects and advantages of the invention will be pointed outspecifically or will become apparent from the following description whenit is considered in conjunction with the appended claims and theaccompanying drawings in which:

In summary, the invention comprises apparatus for conveying a viscousliquid from and to a storage tank and includes a supply pipe throughwhich liquid may be withdrawn from the tank and a return pipe concentricwith the supply pipe and through which heated liquid may be returned tothe tank. One of the pipes terminates at a higher level within the tankthan does the other pipe, and the higher level pipe is provided with asleeve at its lower end which is adjustable axially of such pipe fromoutside the tank so as to vary the effective length of the shorter pipeby an amount such as to enable either pipe to constitute the lower levelpipe. By adjustment of the sleeve the amount of heat transferred fromthe returned liquid to the liquid in the tank can be controlled.

FIG. 1 is a fragmentary side elevational view, partly in section, ofapparatus constructed in accordance with one embodiment of theinvention;

FIG. 2 is an enlarged, transverse sectional view taken on the line 2--2of FIG. 1;

FIG. 3 is a sectional detail of a modified form of the invention; and

FIG. 4 is a schematic diagram of a system with which apparatus accordingto the invention is adapted for use.

Apparatus constructed in accordance with either of the disclosedembodiments of the invention is adapted for use in a system such as thatdisclosed in FIG. 4 wherein a quantity of oil is stored in a tank 1 andis withdrawn by means of a pump 2 for delivery in the direction of thearrow a to an oil burner 3 via a supply line 4. Oil is delivered to theburner 3 at a rate in excess of the burner's capacity. The excess oil isdelivered from the burner to a return line 5 which conveys the oil inthe direction of the arrow b back to the tank 1.

The lines 4 and 5 may be formed of electrically conductive material andmay be joined adjacent the burner ends thereof by a conductive jumper 6.The lines 4 and 5 may be heated electrically by means of a transformer 7having a primary winding 8 connected to a source of alternating energyand a secondary winding 9 connected to the supply line 4 on oppositesides of an electrically insulating sleeve 10 which forms part of thesupply line. If desired, the return line 5 may pass through a steamjacket 11 or the like which is supplied with a heating medium so as toraise the temperature of oil flowing through the return line.

In the embodiment disclosed in FIGS. 1 and 2, the supply line 4 includesa tube or conduit 12 that extends vertically into the tank 1 and isjoined at its upper end to a tee fitting 13. The lower end of the tube12 terminates in an open mouth 14 which is located at a predetermineddistance, such as 5 inches, above the bottom of the tank. The interiorof the conduit 12 forms a passage 15 which communicates with the line 4via the fitting 13.

The conduit 12 is encircled by a concentric, larger diameter conduit 16which is supported at its upper end in a fitting 17 mounted on the tank1 and in communication with a coupling 18 that communicates with thereturn line 5. The lower end of the conduit 16 terminates in an openmouth 19 which occupies a position above the level of the mouth 14 ofthe conduit 12. Since the diameter of the conduit 16 and the coupling 18is larger than that of the conduit 12, an annular space 20 surrounds theconduit 12 and forms a passage for oil discharged from the return line5. A vent opening 16' is provided in the conduit 16 adjacent the upperend of the tank.

Encircling the lower end of the conduit 16 is a sleeve 21 which snugly,but slidably, receives the conduit 16. The sleeve 21 has an axial slot22 in which is accommodated a limit and guide screw 23 and a spacer 24.The screw extends through a threaded opening in the conduit 16. Thearrangement is such that the sleeve 21 is axially adjustable relativelyto the conduit 16 a distance corresponding substantially to the lengthof the slot 22.

Means for adjusting the sleeve 21 axially of the conduit 16, and fromoutside the tank 1, comprises a rod 25 which extends completely throughthe conduit 12 and the fitting 13 and which is fixed at its lower end toa bar 26 which lies below the mouth 14 and is joined at its oppositeends to hanger straps 27 that are fixed to the sleeve 21. The upper endof the rod 25 is threaded as at 28 for reception of an adjusting nut 29and is received in a tubular housing 30 that is threaded into thefitting 13. The housing carries a plug 31 having a seat 32 on which thenut 29 rests. The upper end of the housing 30 is closed by a removablecover 33.

In the position of the sleeve 21 shown in full lines in FIG. 1, itslower end is at the same level as that of the mouth 19 of the returnconduit 16. In this position of the sleeve, oil discharged from themouth 19 of the return line 16 is free to flow downwardly and laterallyso as to warm a considerable volume of oil in the vicinity of the mouthof the supply conduit 12. However, the sleeve 21 may be adjusteddownwardly as indicated in chain lines in FIG. 1, so as to increase theeffective length of the return line. In the adjusted position the lowerend of the sleeve extends to a level below the mouth 14 of the supplyconduit and forms a cowl around the mouth of the supply conduit. Thus,oil discharged through the mouth 19 of the return conduit 16 isprevented by the sleeve from spreading laterally, thereby concentratingthe heat of the returned oil in the immediate vicinity of the mouth 14of the supply conduit.

The axial adjustment of the sleeve 21 is effected quite simply byremoving the cover 33 from the housing 30 and rotating the nut 29 on thethreaded end 28 of the rod 25. The sleeve 21 may be adjusted to anyselected position between its upper and lower limits, and suitableindicia (not shown) may be provided on the upper end of the rod 25 toindicate the extent to which the sleeve projects above and below themouth 14 of the supply conduit 12.

The embodiment shown in FIG. 3 is similar to the earlier describedembodiment but differs from the latter in that the return conduit 16projects below the mouth 14 of the supply conduit 12 so that the mouth19 of the return conduit normally occupies a position below the mouth 14of the supply conduit. In the modified embodiment a sleeve 21a, similarto the sleeve 21, slidably encircles the lower end of the supply conduit12 and is coupled to the adjusting rod 25 by a cross bar 26a. In allother respects, the embodiments of FIGS. 1 and 3 are the same.

The sleeve 21a may be adjusted axially of the conduit 12 from the fullline position shown in FIG. 3 to the chain line position so that, ineffect, the mouth of the supply conduit may be positioned either aboveor below the level of the mouth 19 of the return conduit 16.

In the event the vent opening 16' should become plugged, or should aircollect in the conduit 16 for any other reason, there is a possibilitythat such air would be drawn into the mouth of the supply conduit 12when the latter is at a level higher than that of the mouth 14 andresult in erratic operation of the pump or burner. When air is suspectedof being entrained in the supply conduit, the sleeve 21 or 21a may beraised or lowered, respectively, for a short period of time to allow airto escape into the tank.

The disclosed embodiments are representative of presently preferredforms of the invention, but are intended to be illustrative rather thandefinitive thereof. The invention is defined in the claims.

I claim:
 1. Viscous liquid conveying apparatus comprising a tank havinga bottom for containing a supply of viscous liquid; a device forreceiving liquid from said tank; a supply line extending into said tanktoward said bottom and having one end terminating at a predeterminedlevel from said bottom in an open mouth, said supply line having itsother end connected to said device; a return line having one endextending into said tank in concentric relation with said supply lineand having its other end connected to said device, said one end of saidreturn line terminating in an open mouth adjacent the mouth of saidsupply line but at a different level from said bottom; means fordelivering liquid from said tank to said device via said supply line andfor returning liquid from said device to said tank via said return line;means for heating liquid returned to said tank via said return line; atubular member snugly but slidably fitted on the higher level one ofsaid lines adjacent its mouth for back and forth movements toward andaway from the bottom of said tank to adjust the effective length of saidhigher level one f said lines and thereby the position of its mouth at aselected level above or below the level of the mouth of the other ofsaid lines; and operating means connected to said tubular member formoving the latter.
 2. Apparatus according to claim 1 wherein the mouthof said supply line is at a higher level above said bottom than themouth of said return line and wherein said tubular member is fitted onsaid supply line.
 3. Apparatus according to claim 1 wherein the mouth ofsaid return line is at a higher level above said bottom than the mouthof said supply line and wherein said tubular member is fitted on saidreturn line.
 4. Apparatus according to claim 1 wherein said operatingmeans extends from said tubular member to a position external of saidtank.
 5. Apparatus according to claim 1 including means for maintainingsaid tubular member in any one of a number of selected positions ofadjustment relative to the mouth of said other of said lines. 6.Apparatus according to claim 1 including means reacting between saidtubular member and said one of said lines for guiding said tubularmember in its movements.
 7. Apparatus according to claim 1 wherein saidsupply line is within said return line at said one end of said lines. 8.Viscous liquid conveying apparatus adapted for immersion in a reservoirof liquid for withdrawing and returning liquid from and to saidreservoir, said apparatus comprising a first conduit having an openmouth at one end; a second conduit, said second conduit having an openmouth at one end, said second conduit being positioned within said firstconduit in radially spaced relation therewith and with the open mouthsof said conduits adjacent but axially spaced from one another wherebythe one end of one of said conduits projects beyond the open mouth ofthe other of said conduits; sleeve means snugly but slidably fitted tosaid other of said conduits adjacent its mouth for back and forth axialmovements thereon to vary the effective length of said other of saidconduits and the position of its mouth relative to the mouth of said oneof said conduits an amount sufficient that the mouth of said other ofsaid conduits can be made to selectively project beyond the mouth ofsaid one of said conduits; and operating means connected to said sleevemeans for adjusting the latter.
 9. Apparatus according to claim 8wherein said sleeve means is fitted to said first conduit.
 10. Apparatusaccording to claim 8 wherein said sleeve means is fitted to said secondconduit.
 11. Apparatus according to claim 8 wherein said operating meansextends beyond the opposite end of said conduits.
 12. Apparatusaccording to claim 11 wherein said operating means extends through saidfirst conduit.
 13. Apparatus according to claim 8 including adjustablemeans carried by said operating means for maintaining the latter in aselected position of adjustment.
 14. Apparatus according to claim 8including means reacting between said one of said conduits and saidsleeve means for guiding the latter and limiting the extent of itsadjustment.